The present invention relates to optical transmission equipment, and more particularly, to the improvement of the optical transmission equipment which uses more than one power supply for the circuit elements in the equipment.
Conventional optical transmission equipment prevents malfunction when turning on the power supply, in a manner such as that described in Japanese application patent laid-open publication No. Hei 07-210272. This application discloses to provide a forced discharge circuit in a reset circuit when turning on the power supply to prevent false output of the received output even in the case of power supply voltage return after very short voltage drop.
However, the optical transmission equipment may use a segmented power supply, in cases such as analog and digital mixed circuits used in the equipment, to keep noise generated in one circuit from interfering with other circuits. The optical transmission equipment with more than one integrated circuit also needs different power supply voltages for the circuits. Thus, the optical transmission equipment may often use more than one different power supply to power each circuit element. This may cause an unstable operation or a malfunction of the optical transmission equipment, such as inadequate reading of the desired set information, depending on when each power supply is turned on.